Fungicidal 3-cyano-4-phenyl-pyrroles

ABSTRACT

Fungicidal 3-cyano-4-phenyl-pyrroles of the formula ##STR1## in which R 1  represents chlorine, bromine, alkyl, halogenoalkyl or halogenoalkoxy, 
     R 2  represents chlorine, bromine, alkyl, halogenoalkyl or halogenoalkoxy and 
     R 3  represents hydrogen or fluorine, 
     with the proviso that at least one of the radicals R 1  or R 2  represents halogenoalkyl.

The invention relates to new 3-cyano-4-phenyl-pyrrole derivatives, to aprocess for their preparation, to their use for combating pests, inparticular as fungicides, and to new intermediates.

It has been disclosed that certain 3-cyano-4-phenyl-pyrroles, such as,for example, the compound 3-cyano-4-(2,3-dichlorophenyl)-pyrrole, havefungicidal activity (cf., for example, EP 236,272).

Furthermore, it is known that certainperhalogenoalkylmercapto-sulphonamides and -sulphamides, such as, forexample,N,N-dimethyl-N'-phenyl-N'-(fluorodichloromethylthio)-sulphamide, havefungicidal properties (cf. DAS 1,193,498).

However, the activity of these previously disclosed compounds is notcompletely satisfactory in all areas of application, in particular atlow application rates and concentrations.

New 3-cyano-4-phenyl-pyrrole derivatives of the general formula (I),##STR2## in which R¹ represents chlorine, bromine, alkyl, halogenoalkylor halogenoalkoxy,

R² represents chlorine, bromine, alkyl, halogenoalkyl or halogenoalkoxyand

R³ represents hydrogen or fluorine, with the proviso that at least oneof the radicals R¹ or

R² represents halogenoalkyl, have been found.

Furthermore, it has been found that the new 3-cyano-4-phenyl-pyrroles ofthe general formula (I) ##STR3## in which R¹ represents chlorine,bromine, alkyl, halogenoalkyl or halogenoalkoxy,

R² represents chlorine, bromine, alkyl, halogenoalkyl or halogenoalkoxyand

R³ represents hydrogen or fluorine,

with the proviso that at least one of the radicals R¹ or R² representshalogenoalkyl, are obtained when substituted cinnamonitriles of theformula (II) ##STR4## in which R¹, R² and R³ have the abovementionedmeanings, are reacted with sulphonylmethyl isocyanides of the formula(III),

    R.sup.4 --SO.sub.2 --CH.sub.2 --NC                         (III)

in which

R⁴ represents alkyl or optionally substituted aryl, in the presence of abase and if appropriate in the presence of a diluent.

Finally, it has been found that the new 3-cyano-4-phenyl-pyrroles of thegeneral formula (I) have a good action against pests.

Surprisingly, the 3-cyano-4-phenyl-pyrroles of the general formula (I)according to the invention show a considerably better fungicidalactivity than, for example, the 3-cyano-4-phenyl-pyrroles andperhalogenoalkylmercapto-sulphonamides and -sulphamides known from theprior art, such as 3-cyano-4-(2,3-dichloro-phenyl)pyrrole andN,N-dimethyl-N'-phenyl-N'-(fluorodichloromethylthio)-sulphamide, whichare closely related compounds chemically and with respect to theiraction.

Preferred substituents or ranges of the radicals shown in the formulaementioned above and below are illustrated in the following:

In the general formulae, alkyl in general denotes straight-chain orbranched alkyl having 1 to 6 carbon atoms, preferably having 1 to 4 andparticularly preferably having 1 or 2 carbon atoms; examples which maybe mentioned are methyl, ethyl, n- and i-propyl, n-, i-, s- and t-butyl,pentyl and hexyl.

Halogenoalkyl and halogenoalkoxy, as substituents in the radicals, ingeneral represent straight-chain or branched radicals each having 1 to 4carbon atoms, particularly preferably having 1 or 2 carbon atoms and ineach case having 1 to 9, or 1 to 5, identical or different halogen atomsas defined under halogen; examples which may be mentioned are:fluoromethyl, chloromethyl, bromomethyl, fluoroethyl, chloroethyl,bromoethyl, fluoro-n-propyl, chloro-n-propyl, difluoromethyl,tri-fluoromethyl, dichloromethyl, trichloromethyl, difluoroethyl,trifluoroethyl, trichloroethyl, chloro-difluoromethyl,trifluoro-chloroethyl, chlorobutyl, fluorobutyl, fluoromethoxy,chloromethoxy, bromomethoxy, fluoroethoxy, chloroethoxy, bromoethoxy,fluoropropoxy, chloropropoxy, bromopropoxy, fluorobutoxy, chlorobutoxy,fluoro-i-propoxy, chloro-i-propoxy, difluoromethoxy, trifluoromethoxy,dichloromethoxy, trichloromethoxy, difluoroethoxy, trifluoroethoxy,tetrafluoroethoxy, trichloroethoxy, chlorodifluoromethoxy andtrifluorochloroethoxy, trifluoromethyl and trifluoromethoxy beingparticularly emphasized.

Halogen in the definitions of halogenoalkyl and halogenoalkoxyrepresents fluorine, chlorine, bromine and/or iodine, in particularfluorine, chlorine and/or bromine and particularly fluorine or chlorine.

Formula (I) provides the general definition of the3-cyano-4-phenyl-pyrroles according to the invention. Preferredcompounds of the formula (I) are those in which

R¹ represents chlorine, bromine, straight-chain or branched alkyl having1 to 4 carbon atoms or in each case straight-chain or branchedhalogenoalkyl or halogenoalkoxy in each case having 1 to 4 carbon atomsand 1 to 9 identical or different halogen atoms,

R² represents chlorine, bromine, straight-chain or branched alkyl having1 to 4 carbon atoms or in each case straight-chain or branchedhalogenoalkyl or halogenoalkoxy in each case having 1 to 4 carbon atomsand 1 to 9 identical or different halogen atoms and

R³ represents hydrogen or fluorine,

with the proviso that at least one of the radicals R¹ or R² representshalogenoalkyl.

Particularly preferred compounds of the formula (I) are those in which

R¹ represents chlorine, bromine, methyl, ethyl, trifluoromethyl ortrifluoromethoxy,

R² represents chlorine, bromine, methyl, ethyl, trifluoromethyl ortrifluoromethoxy and

R³ represents hydrogen or fluorine,

with the proviso that at least one of the radicals R or R² representstrifluoromethyl.

Very particularly preferred compounds of the formula (I) which may bementioned are: 3-cyano-4-(2-methyl-3-trifluoromethylphenyl)-pyrrole and3-cyano-4-(2,3-di-trifluoromethylphenyl)pyrrole.

The preferred definitions indicated for the compounds of the formula (I)also apply to the starting compounds of the formula (II).

The following 3-cyano-4-phenyl-pyrroles of the general formula (I) maybe mentioned individually in addition to the compounds mentioned in thepreparation examples: ##STR5##

                  TABLE 1                                                         ______________________________________                                        R.sup.1          R.sup.2      R.sup.3                                         ______________________________________                                        CF.sub.3         Cl           H                                               CF.sub.3         CH.sub.3     H                                               CF.sub.3         OCF.sub.3    H                                               CF.sub.3         Br           H                                               Cl               CF.sub.3     H                                               Br               CF.sub.3     H                                               OCF.sub.3        CF.sub.3     H                                               CF.sub.3         Cl           4F                                              CF.sub.3         Cl           5F                                              CF.sub.3         CH.sub.3     4F                                              CF.sub.3         CH.sub.3     5F                                              CF.sub.3         OCF.sub.3    4F                                              CF.sub.3         OCF.sub.3    5F                                              Cl               CF.sub.3     4F                                              Cl               CF.sub.3     5F                                              Br               CF.sub.3     4F                                              Br               CF.sub.3     5F                                              OCF.sub.3        CF.sub.3     4F                                              OCF.sub.3        CF.sub.3     5F                                              CH.sub.3         CF.sub.3     4F                                              CH.sub.3         CF.sub.3     5F                                              ______________________________________                                    

If, for example, 2-methyl-3-trifluoromethyl cinnamonitrile andp-toluenesulphonylmethyl isocyanide are used as starting substances andsodium hydride as the base, the course of the reaction of the processaccording to the invention can be represented by the following equation:##STR6##

Formula (II) provides a general definition of the substitutedcinnamonitriles required as starting substances for carrying out theprocess according to the invention. In this formula (II), R¹, R² and R³preferably represent those radicals which have already been mentioned aspreferred for these substituents in connection with the description ofthe substances of the formula (I) according to the invention.

The substituted cinnamonitriles of the formula (II) are new. However,they are obtained in analogy to known methods (cf., for example, DE-OS(German Published Specification) 2,927,480), for example when

a) anilines of the formula (IV) ##STR7## in which R¹, R² and R³ have theabovementioned meanings, with the proviso that at least one of theradicals R¹ or R² represents halogenoalkyl, are reacted in a first stepwith acrylonitrile under customary diazotization conditions, for examplein the presence of sodium nitrite and hydrochloric acid, and in thepresence of a suitable metal salt catalyst, such as, for example,copper(II) chloride or copper(II) oxide, and if appropriate in thepresence of a suitable diluent, such as, for example, acetone or water,at temperatures between -20° C. and 50° C. ("Meerwein arylation"; cf.also here Organic Reactions 11, 189 [1960]; Organic Reactions 24. 225[1976] or C. Ferri in "Reaktionen der organischen Synthese" (Reactionsof organic synthesis) p. 319, Thieme Verlag Stuttgart 1978) and then ina second step dehydrohalogenating the substitutedα-chloro-β-phenylpropionitriles thus obtained of the formula (V)##STR8## in which R¹, R² and R³ have the abovementioned meanings, withthe proviso that at least one of the radicals R¹ or R² representshalogenoalkyl, with bases, such as, for example triethylamine ordiazabicycloundecene, in a customary manner, if appropriate in thepresence of a diluent, such as, for example, tetrahydrofuran, attemperatures between 0° C. and 50° C. (cf. also the preparationexamples) or alternatively when

b) benzaldehydes of the formula (VI) ##STR9## in which R¹, R² and R³have the abovementioned meanings, with the proviso that at least one ofthe radicals R¹ or R² represents halogenoalkyl, are condensed withcyanoacetic acid of the formula (VII)

    NC--CH.sub.2 --COOH                                        (VII)

and simultaneously decarboxylated in a customary manner in the presenceof a base, such as, for example, piperidine or pyridine, and ifappropriate in the presence of a suitable diluent, such as, for example,pyridine, at temperatures between 50° C. and 120° C. (cf., for example,"Organikum" p. 571/572; 15th edition; VEB Deutscher Verlag derWissenschaften Berlin 1981 and also the Preparation Examples).

The anilines of the formula (IV) are known in some cases (cf., forexample, DE-OS (German Published Specification) 3,726,891, JP62,298,562, EP-OS 206,951, JP 61,083,146) or are obtainable in analogyto known methods.

The benzaldehydes of the formula (VI) required as precursors for thepreparation of the new starting products of the formula (II) accordingto variant b) are for the most part known (cf., for example, EP 225,175,EP 125,803, EP 174,131, EP 169,009, EP 168,151, EP 145,334, U.S. Pat.No. 4,572,909, JP 84,118,782, J. Chem. Soc., Perkin Trans. 1, 1837-1844and J. Med. Chem. 29, 1696-1702). Cyanoacetic acid of the formula (VII)is also a generally known compound of organic chemistry.

Formula (III) provides a general definition of the sulphonylmethylisocyanides furthermore required as starting substances for carrying outthe process according to the invention. In this formula (III), R⁴preferably represents alkyl having 1 to 4 carbon atoms, particularlypreferably methyl or optionally monosubstituted phenyl, such as, forexample, 4-methylphenyl or 4-chlorophenyl, or phenyl.

The sulphonylmethyl isocyanides of the formula (III) are known (cf., forexample, Synthesis 1985, 400-402; Org. Syntheses 57, 102-106 [1977]; J.org. Chem. 42, 1153-1159 [1977]; Tetrahedron Lett. 1972, 2367-2368).

Possible diluents for carrying out the process according to theinvention are inert organic solvents. In particular, these includealiphatic, alicyclic or aromatic, optionally halogenated hydrocarbons,such as, for example, benzine, benzene, toluene, xylene, chlorobenzene,petroleum ether, hexane, cyclohexane, dichloromethane, chloroform,carbon tetrachloride, ethers, such as diethyl ether, dioxane,tetrahdyrofuran or ethylene glycol dimethyl ether or ethylene glycoldiethyl ether, amides, such as dimethylformamide, dimethylacetamide,N-methylformanilide, N-methylpyrrolidone or hexamethylphosphoramide, orsulphoxides, such as dimethyl sulphoxide.

The process according to the invention can optionally also be carriedout in a two-phase system, such as, for example, water/toluene orwater/dichloromethane, if appropriate in the presence of aphase-transfer catalyst. Examples of such catalysts which may bementioned are: tetrabutylammonium iodide, tetrabutylammonium bromide,tributyl-methylphosphonium bromide, trimethyl-C₁₃ /C₁₅ -alkylammoniumchloride, dibenzyldimethyl-ammonium methylsulphate, dimethyl-C₁₂ /C₁₄-alkylbenzylammonium chloride, tetrabutylammonium hydroxide, 15-crown-5,18-crown-6, triethylbenzylammonium chloride and trimethylbenzylammoniumchloride.

The process according to the invention is preferably carried out in thepresence of a suitable base. Those which are suitable are allcustomarily utilizable inorganic and organic bases. Hydrides,hydroxides, amides, alkoxides, carbonates or hydrogen carbonates ofalkali metals, such as, for example, sodium hydride, sodium amide,sodium hydroxide, sodium methoxide, sodium ethoxide, potassiumt-butoxide, sodium carbonate or sodium hydrogen carbonate and alsotertiary amines, such as, for example, triethylamine,N,N-dimethylaniline, pyridine, N,N-dimethylaminopyridine,diazabicyclooctane (DABCO), diazabicyclononene (DBN) ordiazabicycloundecene (DBU) are preferably used.

The reaction temperatures can be varied within a relatively wide rangewhen carrying out the process according to the invention. In general,the reaction is carried out at temperatures between -30° C. and +120°C., preferably at temperatures between -20° C. and +50° C.

For carrying out the process according to the invention, 1.0 to 2.0moles, preferably 1.0 to 1.5 moles, of sulphonylmethyl isocyanide of theformula (III) and 1.0 to 2.0 moles, preferably 1.0 to 1.5 moles, of baseare in general employed per mole of substituted cinnamonitrile of theformula (II).

In this connection, it may be advantageous to carry out the reaction inthe presence of a protective gas atmosphere such as, for example, argon.The reaction is carried out, and the reaction products are worked up andisolated by generally customary methods.

Alternatively to the preparation of the active compounds according tothe invention with the aid of the preparation process according to theinvention, various other preparation processes for the preparation ofthe active compounds according to the invention are conceivable.

Thus, active compounds of the formula (I) according to the invention arealso obtained, for example, when α-cyanocinnamic acid esters are reactedwith p-toluenesulphonylmethyl isocyanide in the presence of bases and inthe presence of copper(II) salts (cf. J6-1030-571 or J6-1200-984) orwhen α-substituted cinnamonitriles are cyclized with isocyanoacetic acidesters in the presence of sodium hydride, and the pyrrole-2-carboxylicacid esters thus obtained are hydrolyzed with bases and then thermallydecarboxylated (cf. JP 59/212,468) or when phenacylamine derivatives arereacted with suitably substituted acrylonitrile derivatives (cf. EP174,910) or when 3-trifluoromethyl-4-phenyl-pyrroles are reacted withammonia at elevated temperature and elevated pressure (cf EP 182,738) orwhen 3-cyano-4-phenyl-Δ² -pyrrolines are oxidized in the presence ofcopper(II) salts or iron(III) salts (cf. EP 183,217) or whenα-cyanoacrylic acid derivatives are reacted with isocyanoacetic acidesters in the presence of a base and the Δ² -pyrroline-2-carboxylic acidderivatives thus obtained are oxidatively decarboxylated in a secondstep in the presence of a base and in the presence of a metal saltcatalyst (cf. German Patent Application P 3,718,375 of 02.06.1987).

The active compounds according to the invention have a strong actionagainst pests and can be employed practically for combating undesiredinjurious organisms. The active compounds are suitable for use as plantprotection agents, in particular as fungicides.

Fungicidal agents in plant protection are employed for combatingPlasmodiophoromycetes, Oomycetes, Chytridiomycetes, Zygomycetes,Ascomycetes, Basidiomycetes and Deuteromycetes.

Some causative organisms of fungal diseases which come under the genericnames listed above may be mentioned as examples, but not by way oflimitation: Pythium species, such as, for example, Pythium ultimum;Phytophthora species, such as, for example, Phytophthora infestans;

Pseudoperonospora species, such as, for example, Pseudoeronospora humulior Pseudoperonospora cubensis;

Plasmopara species, such as, for example, Plasmopara viticola;

Peronospora species, such as, for example, Peronospora pisi or P.brassicae;

Erysiphe species, such as, for example, Erysiphe graminis;

Sphaerotheca species, such as, for example, Sphaerotheca fuliginea;

Podosphaera species, such as, for example, Podosphaera leucotricha;

Venturia species, such as, for example, Venturia inaequalis;

Pyrenophora species, such as, for example, Pyrenophora teres or P.graminea (conidia form: Drechslera, syn: Helminthosporium);

Cochliobolus species, such as, for example, Cochliobolus sativus(conidia form: Drechslera, syn: Helminthosporium);

Uromyces species, such as, for example, Uromyces appendiculatus;

Puccinia species, such as, for example, Puccinia recondita;

Tilletia species, such as, for example, Tilletia caries;

Ustilago species, such as, for example, Ustilago nuda or Ustilagoavenae;

Pellicularia species, such as, for example, Pellicularia sasakii;

Pyricularia species, such as, for example, Pyricularia oryzae;

Fusarium species, such as, for example, Fusarium culmorum;

Botrytis species, such as, for example, Botrytis cinerea;

Septoria species, such as, for example, Septoria nodorum;

Leptosphaeria species, such as, for example, Leptosphaeria nodorum;

Cercospora species, such as, for example, Cercospora canescens;

Alternaria species, such as, for example, Alternaria brassicae and

Pseudocercosporella species, such as, for example, Pseudocercosporellaherpotrichoides.

The good toleration, by plants, of the active compounds, at theconcentrations required for combating plant diseases, permits treatmentof above-ground parts of plants, of vegetative propagation stock andseeds, and of the soil.

The active compounds according to the invention can be employed herewith particularly good effect for combating diseases in fruit andvegetable cultivation, such as, for example, against the causativeorganism of brownish-grey mildew of beans (Botrytis cinerea) or forcombating rice diseases such as, for example, against the causativeorganism of rotten neck of rice (Pyricularia oryzae) or against Erysiphegraminis on barley.

Furthermore, some of the active compounds according to the inventionshow good fungicidal actions against Venturia on apple, Pellicularia onrice, Leptosphaeria, Cochliobolus, Pyrenophora and Fusarium on cerealcultures. In addition, some of the active compounds according to theinvention also show a good in vitro action.

Depending on their individual physical and/or chemical properties, theactive compounds can be converted into the customary formulations, suchas solutions, emulsions, suspensions, powders, foams, pastes, granules,aerosols, very fine capsules in polymeric substances and in coatingcompositions for seed, as well as ULV cold and warm mist formulations.

These formulations are produced in a known manner, for example by mixingthe active compounds with extenders, that is, liquid solvents, liquefiedgases under pressure and/or solid carriers, optionally with the use ofsurface-active agents, that is, emulsifying agents and/or dispersingagents and/or foam-forming agents. In the case of the use of water as anextender, organic solvents can, for example, also be used as auxiliarysolvents. As liquid solvents, there are suitable in the main: aromatics,such as xylene, toluene or alkylnaphthalenes, chlorinated aromatics orchlorinated aliphatic hydrocarbons, such as chlorobenzenes,chloroethylenes or methylene chloride, aliphatic hydrocarbons, such ascyclohexane or paraffins, for example mineral oil fractions, alcohols,such as butanol or glycol as well as their ethers and esters, ketones,such as acetone, methyl ethyl ketone, methyl isobutyl ketone orcyclohexanone, strongly polar solvents, such as dimethylformamide anddimethyl sulphoxide, as well as water; by liquefied gaseous extenders orcarriers are meant liquids which are gaseous at ambient temperature andunder atmospheric pressure, for example aerosol propellants, such ashalogenated hydrocarbons as well as butane, propane, nitrogen and carbondioxide. As solid carriers there are suitable: for example groundnatural minerals, such as kaolins, clays, talc, chalk, quartz,attapulgite, montmorillonite or diatomaceous earth, and ground syntheticminerals, such as highly-disperse silica, alumina and silicates; assolid carriers for granules there are suitable: for example crushed andfractionated natural minerals such as calcite, marble, pumice, sepioliteand dolomite, as well as synthetic granules of inorganic and organicmeals, and granules of organic material such as sawdust, coconut shells,corn cobs and tobacco stalks. As emulsifying and/or foam-forming agentsthere are suitable: for example non-ionic and anionic emulsifiers, suchas polyoxyethylene fatty acid esters, polyoxyethylene fatty alcoholethers, for example alkylaryl polyglycol ethers, alkylsulphonates, alkylsulphates, arylsulphonates as well as albumin hydrolysis products; asdispersing agents there are suitable: for example lignin-sulphite wasteliquors and methylcellulose.

Adhesives such as carboxymethylcellulose and natural and syntheticpolymers in the form of powders, granules or latices, such as gumarabic, polyvinyl alcohol and polyvinyl acetate, as well as naturalphospholipids, such as cephalins and lecithins, and syntheticphospholipids, can be used in the formulations. Other additives can bemineral and vegetable oils.

It is possible to use colorants such as inorganic pigments, for exampleiron oxide, titanium oxide and Prussian Blue, and organic dyestuffs,such as alizarin dyestuffs, azo dyestuffs and metal phthalocyaninedyestuffs, and trace nutrients such as salts of iron, manganese, boron,copper, cobalt, molybdenum and zinc.

The formulations in general contain between 0.1 and 95 per cent byweight of active compound, preferably between 0.5 and 90%.

The active compounds according to the invention can be present in theformulations as a mixture with other known active compounds, such asfungicides, insecticides, acaricides and herbicides, as well as inmixtures with fertilizers and growth regulators.

The active compounds can be used as such or in the form of theirformulations or the use forms prepared therefrom, such as ready-to-usesolutions, suspensions, wettable powders, pastes, soluble powders, dustsand granules. They are used in the customary manner, for example bywatering, spraying, atomizing, scattering, dusting, foaming, brushing onand the like. It is furthermore possible to apply the active compoundsby the ultra-low volume method or to inject the active compoundformulation or the active compound itself into the soil. The seeds ofthe plants can also be treated.

In the treatment of parts of plants, the active compound concentrationsin the use forms can be varied within a substantial range. They are, ingeneral, between 1 and 0.0001% by weight, preferably between 0.5 and0.001%.

In the treatment of seed, amounts of active compound of 0.001 to 50 gper kilogram of seed, preferably 0.01 to 10 g, are generally required.

For treatment of the soil, active compound concentrations of 0.00001 to0.1% by weight, preferably 0.0001 to 0.02% by weight, are required atthe place of action.

PREPARATION EXAMPLES Example 1 ##STR10##

A solution of 5.0 g (0.0237 mol) of3-(2-methyl-3-trifluoromethyl-phenyl)-acrylonitrile and 6.0 g (0.0308mol) of p-toluenesulphonylmethyl isocyanide in 20 ml of a mixture oftetrahydrofuran/dimethyl sulphoxide (6:1) is added dropwise at -10° C.to -20° C. with stirring to 1.0 g (0.033 mol) of sodium hydride (80%strength in mineral oil) in 17.0 ml of tetrahydrofuran under an argonatmosphere. After completion of the addition, the reaction mixture isallowed to come to room temperature, water is added, the mixture isextracted several times with ethyl acetate, and the combined ethylacetate phases are washed with water, dried over sodium sulphate andconcentrated in vacuo. The residue is purified by chromatography onsilica gel (eluent: cyclohexane/ethyl acetate 5:1).

4.5 g (76% of theory) of3-cyano-4-(2-methyl-3-trifluoromethylphenyl)-pyrrole of melting point99° C.-100° C. are obtained.

Example 2

3-Cyano-4-(2,3-di-trifluoromethyl-phenyl)-pyrrole of melting point 147°C.-149° C. is obtained in an analogous manner to Example 1 and withconsideration for the instructions in the description of the processaccording to the invention.

PREPARATION OF THE STARTING COMPOUNDS Example II-1 ##STR11##

14.4 g (0.094 mol) of diazabicycloundecene are added dropwise at roomtemperature with stirring to 21.2 g (0.086 mol) of2-chloro-3-(2-methyl-3-trifluoromethyl-phenyl)-propionitrile in 120 mlof tetrahydrofuran, the mixture is stirred at room temperature for 15hours after completion of the addition and filtered, the filtrate isconcentrated in vacuo, the residue is taken up in ethyl acetate, washedsuccessively with 1 normal hydrochloric acid and water and dried oversodium sulphate, and the solvent is removed in vacuo.

After distillation in a bulb tube distillation apparatus, 7.9 g (44% oftheory) of 3-(2-methyl-3-trifluoromethyl-phenyl)-acrylonitrile ofmelting point 87° C.-88° C. are obtained.

Example II-2

3-(2,3.Di-trifluoromethyl-phenyl)-acrylonitrile is obtained in ananalogous manner to Example (II-1) and according to the generalinstructions for the preparation. The ¹ H-NMR spectra (CDCl₃) δ=5.7-5.91H (dd, dd)ppm were recorded in deuterochloroform (CDCl₃) usingtetramethylsilane (TMS) as an internal standard. The chemical shift isindicated as the δ value in ppm.

Example V-1 ##STR12##

20 mol of concentrated hydrochloric acid is added at 0°-5° C. to asuspension of 16.7 g of 2-methyl-3-trifluoromethylaniline (0.095 mol) in50 ml of water and the mixture is then briefly warmed to 60°-80° C.until a clear solution has formed. The solution is cooled very rapidlyto 0°-5° C. with vigorous stirring, 22.4 ml (0.286 mol) of acrylonitrileare added dropwise to the fine suspension at 0°-5° C. and a solution of6.75 g of sodium nitrite in 10 ml of water is then rapidly added, andthe mixture is kept at 5° C. for a further 5 minutes and stirred at 20°C. for 1 hour. After cooling, 0.8 g of copper(II) oxide powder is addedto the reaction mixture at 0°-10° C. in portions, a vigorous evolutionof nitrogen gas occurring. After completion of the evolution of gas, themixture is stirred for a further 2 hours at 0°-10° C., then for 15 hoursat room temperature, dichloromethane is added, and the mixture is washedwith water, dried over sodium sulphate and concentrated in vacuo. 21.2 g(90% of theory) of2-chloro-3-(2-methyl-3-trifluoromethylphenyl)-propionitrile are obtainedas a brown oil.

M/e 247 (⁺), 228, 212, 173 (100%)

Example V-2

2-Chloro-3-(2,3-di-trifluoromethyl-phenyl)propionitrile is obtained inan analogous manner to Example (V-1) and according to the generalinstructions for the preparation.

M/e 301 (M⁺), 282, 246, 227 (100%), 177.

Use Examples

The compounds shown below were employed as comparison substances in thefollowing Use Examples: ##STR13##

Example A

    ______________________________________                                        Botrytis test (dwarf beans)/protective                                        ______________________________________                                        Solvent:     4.7 parts by weight of acetone                                   Emulsifier:  0.3 parts by weight of alkylaryl poly-                                        glycol ether                                                     ______________________________________                                    

To produce a suitable preparation of active compound, 1 part by weightof active compound is mixed with the stated amounts of solvent andemulsifier, and the concentrate is diluted with water to the desiredconcentration.

To test for protective activity, young plants are sprayed with thepreparation of active compound until dripping wet. After the spraycoating has dried on, 2 small pieces of agar covered with Botrytiscinerea are placed on each leaf. The inoculated plants are placed in adarkened humid chamber at 20° C. 3 days after the inoculation, the sizeof the infected spots on the leaves is evaluated.

In this test, for example, the compound according to Preparation Example1 shows a clearly superior action compared to the prior art.

Example B

    ______________________________________                                        Pyricularia test (rice)/protective                                            ______________________________________                                        Solvent:    12.5 parts by weight of acetone                                   Emulsifier:  0.3 parts by weight of alkylaryl poly-                                       glycol ether                                                      ______________________________________                                    

To produce a suitable preparation of active compound, 1 part by weightof active compound is mixed with the stated amount of solvent, and theconcentrate is diluted with water and the stated amount of emulsifier tothe desired concentration.

To test for protective activity, young rice plants are sprayed with thepreparation of active compound until dripping wet. After the spraycoating has dried on, the plants are inoculated with an aqueous sporesuspension of Pyricularia oryzae. The plants are then placed in agreenhouse at 100% relative atmospheric humidity and 25° C.

Evaluation of the disease infestation is carried out 4 days after theinoculation.

In this test, for example, the compound according to Preparation Example1 shows a clearly superior action compared to the prior art.

Example C

    ______________________________________                                        Erysiphe test (barley)/protective                                             ______________________________________                                        Solvent:    100 parts by weight of dimethyl                                               formamide                                                         Emulsifier: 0.25 parts by weight of alkylaryl poly-                                       glycol ether                                                      ______________________________________                                    

To produce a suitable preparation of active compound, 1 part by weightof active compound is mixed with the stated amounts of solvent andemulsifier, and the concentrate is diluted with water to the desiredconcentration.

To test for protective activity, young plants are sprayed with thepreparation of active compound until dew-moist. After the spray coatinghas dried on, the plants are dusted with spores of Erysiphe graminisf.sp. hordei.

The plants are placed in a greenhouse at a temperature of about 20° C.and a relative atmospheric humidity of about 80%, in order to promotethe development of powdery mildew pustules.

Evaluation is carried out 7 days after the inoculation.

In this test, for example, the compound according to Preparation Example1 shows a clearly superior action compared to the prior art.

It is understood that the specification and examples are illustrativebut not limitative of the present invention and that other embodimentswithin the spirit and scope of the invention will suggest themselves tothose skilled in the art.

We claim:
 1. A 3-cyano-4-pyrrole of the formula ##STR14## in which oneof R¹ and R² is CF₃ and the other is alkyl having 1 to 4 carbon atoms orCF₃, andR³ is H or F.
 2. A compound according t claim 1, in which one ofR¹ and R² is CF₃ and the other is methyl or ethyl.
 3. A compoundaccording to claim 1, wherein such compound is3-cyano-4-(2-methyl-3-trifluoromethylphenyl)-pyrrole of the formula##STR15##
 4. A fungicidal composition comprising a fungicidallyeffective amount of a compound according to claim 1 and a diluent.
 5. Amethod of combating fungi which comprises applying to such fungi or to afungus habitat a fungicidally effective amount of a compound accordingto claim
 1. 6. A method of combating fungi which comprises applying tosuch fungi or to a fungus habitat a fungicidally effective amount of acompound according to claim 4.